Mr Sabyasachi Majumdar1, Dr Nagabovanalli B. Prakash1
1University Of Agricultural Sciences, Bangalore, Bangalore, India, 2University Of Agricultural Sciences, Bangalore, Bangalore, India
Although numerous studies have indicated the importance of silicon (Si) for various crops and substantial contribution of agricultural ecosystems to global carbon (C) balance, yet the Si-C interaction in agricultural ecosystems have not been well recognised and/or understood poorly so far. An attempt was made to explore the prospects of any possible relationship existing between the carbon fractions [total organic carbon (TOC), inorganic carbon (IC) and total carbon (TC)] and readily soluble Si pools [viz., dissolved Si (DSi), adsorbed Si (AdSi) and amorphous Si (ASi) from profile soil samples collected from four different agro-climatic zones [southern dry zone (SDZ), southern transition zone (STZ), coastal zone (CZ) and central dry zone (CDZ)] of Karnataka where rice and sugarcane were being continuously cultivated for more than a decade. Irrespective of the crop, AdSi and ASi showed negative correlation with TOC and TC, whereas DSi recorded positive and negative correlation with TOC and IC, respectively. However in soil profiles of sugarcane, AdSi correlated significantly and negatively with TOC whereas significant positive correlation noticed between DSi and TOC. This suggests that TOC may perhaps act as a potential source of readily soluble Si or DSi in rice and sugarcane soils of Karnataka. In rice soils of SDZ, TC recorded significant positive correlation with DSi. However, ASi showed significant positive correlation with TOC and TC but correlated significantly negatively with IC in rice soils of CDZ. Therefore, TC and TOC are the main source of DSi and ASi in rice soils of SDZ and CDZ, respectively. Moreover, in sugarcane soils of CZ, DSi correlated significantly and positively with TOC and TC which might be attributed to higher TOC and TC content recorded in CZ. Hence, TOC and TC can be considered as a potential source of DSi in sugarcane soils of CZ. However, DSi showed significant negative correlation with TOC and TC in sugarcane soils of CDZ. Thus, it can be concluded that in sugarcane soils of CDZ, IC is a main source for DSi. This can be validated by the higher pH prevailing in CDZ which might have resulted in accumulation of higher calcium carbonates that act as a source of IC.
Mr. Sabyasachi Majumdar registered at University of Agricultural Sciences, Bangalore in the Department of Soil Science and Agricultural Chemistry for pursuing his Ph.D during July 2014. He is working on the topic “Quantification of readily soluble silicon pools, carbon fractions and distribution of phytoliths in rice and sugarcane soils” under the supervision of Dr. N. B. Prakash. Mr. Majumdar has been awarded with prestigious INSPIRE Fellowship by Department of Science and Technology, Ministry of Science and Technology, New Delhi, Government of India during 2015 for a period of five years. He has worked as INSPIRE-JRF from 08-04-2015 to 20-04-2017 and since 21-04-2017 he is working as INSPIRE-SRF. Mr. Majumdar has cleared the comprehensive examination for Ph.D with flying colours and recently submitted his thesis for external evaluation.